Improvement in the method of finishing the heads of screws



T. J. SLOAN.

Making Screws.

Patented June I0, 1851.

law a c F I N. PETERS. Photo-Lihugrapher. Washingfian. D. C.

give a bad finishto the work.

UNITED STATES PATENT OFFICE.

THOMAS J. SLOAN, OF NEW YORK, N. Y.

IMPROVEMENT IN THE METHOD OF FINTSHING THE HEADS 0F SCREWS.

Specification forming part of Letters Patent No. 8,155, dated June 10, 1851.

I 2 the blank after the first, and Fig. 3 the same after the second or final, shaving operation. Fig. 4 is aplan of the machine employed; Fig.

' 5,- an end elevation; Fig. 6, a side elevation;

Fig.7, elevations of the twocams employed to operate the cutters for the two successive operations, and Fig. 8 is a View of the two cutters for the two operations.

, The same letters indicate like parts in all the figures.

j, The mode of procedure for finishing the heads of screw-blanks, as heretofore and now practiced, is first to shave'thehead and then to cut the nick, which last operation leaves v burrs on the periphery of the head that are objectionable, for the reason that in using the screws these burrs scrape when inserted and If to avoid this the head be nicked before it is shaved, then the cutters in shaving frequently, if not in variably, break off the metal at two of the angles formed by theline of the nick and the periphery. of the head, because the angle angle, bringing it ultimately, however, to the required diameter, then to cut the nick, and finally to finish the shaving operation on the head with a cutter presenting a more acute angle, which merely finishes the top and bevel of the head, and which, forming amore acute angle than the first, will begin to out toward the center on top and from the shank on the bevel toward the periphery, when it merely shaves off slightly to givea finish. In this way the head. of the screw is finished without aburr, and the metal is not exposed toa strain which will be likely to break of the metal at the angles formed by the lines of the nick and the periphery of the head, for the cutter has only a finishing action on that part of the head in which the nick has been formed, and when it gives the finishing cut to the bevel when the nick is formed it is kept steady and prevented from partly entering the nick by bearing against that part of the bevel below the nick. p y

In the accompanying drawings, 0 represents the frame of the machine, which'l have employed with success for this purpose, and b the mandrel receiving motion from some first mover in the usual Way of driving the mandrel in machines for threading screws. The forward end of this mandrel carries gripping jaws in which the screw-blanks are held to be rotated, with the head and so much of the shank projecting out as to receive'a rest c, attached to a head d, to support the blank during the action of the cutter on it. The head cl is attached to andvibrates with a rock-shaft e. The rest is drawn back from the blank by a spring f and forced up to it by an arm g (with a rocker h interposed) on a rock-shaft i, which rock-shaft has another arm j, that bears against the periphery of a cam is on the cam-shaft Z, which derives motion from the mandrel byapinion m and 00,,- wheel a in theproportion of one to.ten,which proportion, however, may be varied at pleasure. The form of this cam is such (as represented in the accompanying drawings) that the moment the blank is gripped it shall force I The cutter 0 is mounted in a cutter-stock 19, attached to a rock-shaft q, whose axis is placed at such an angle with the line of the mandrel that the line of motion of the cutter toward the blank shall coincide with a line midway between the top and the bevel of the head, so as to approach both surfaces equally. The cutter-stock is drawn back by a spring 0 and forced up toward the blank by an arm 8 (a rockert being interposed to avoid frietion) on a rock-shaft u, provided with another arm 11, that bears against the periphery of a cam w on the cam-shaft. The form of this cam and its position relatively to the cam that operates the rest is such that so soon as the rest is carried up against the blank the cutter is moved up with a rapid motion until it begins to cut, and then by a regular and slow motion it is moved toward the axis of the blank to effect the shaving of the head, and then'it permits the cutter to be drawn back suddenly by the spring.

. The arm 1; on the rock-shaft u is secured thereon by a screw or, so that it canbe shifted from the cam w to another cam y by the side of the cam w for the second shaving operation. These two cams are of nearly-thesame form as represented in Figs. 4 and 7 of the accompanying drawings; but the one y'is of greater radius at the point to carry the cut ter farther toward the axis of the blank at the commencement of the second shaving operation, and from that point the increasing diameter is more gradual than in the cam 10,

- as the range of motion of the cutter is less during the second than the first shaving operation.

The cutter 0- for the first shaving operation is made with the two cutting-edges a b inclined toeach other at an angle more obtuse than the angle formed by the top and bevel of the headof the screw when completed, as

Y the object of the first shaving operation is to shave off the head of the blank along the lines to 0'', so as to bring the periphery-of the head to theultimate required diameter Without materially reducing the thickness and strength of the metal; but after it has been nicked, which is to be done in any of the well-known machines for nicking screws, then it is to be put into the machine with the arm 1) shifted on the rock-shaft, so as to be acted upon by thecam y'for the second or finishing shave, which is done with the other cutter 0, the two cutting-edges a b of which form a more acute angle than in the first, and correspond ving' 'to the form to be given to the head when finished. This cutter will reduce the head to oorrespond with the lines d d, (see Fig. 3,)

from which it will be seen that very little is to be cut away at or near the periphery of the head, the cutter simply takingoif what may be called a finishing-shaving to remove the burrs from that part of the bevel through which the nick has been formed, the cutter being supported during that part of the operation by bearing against and working on that part of the bevel of the head below the nick.

It will be obvious that in practice where screws are manufactured on an extensive scale, instead of making the shaving-machine with the two earns 20 and y and an arm to be shifted from the one to the other for the first andsec- 0nd shaving operations, one set of the machines can be made with the cam w and cutter 0 for the first shaving operation, and another set with the cam 31 and cutter o for the second shaving operation; butit is preferable to use one set of machines for both operations in succession by shiftingthe arm on the rock-shaft and the cutter after a given number of blanks have undergone-the first shaving and the nicking operations, for the blank having been once gripped by the jaws in the mandrel will be again gripped and held in thesame manner.

I have not herein described the mode of feeding in the blanks and operating the gripping-jaws, as this can be done in any of ,the well-known modes before adopted in machinery for shaving screw-blanks. I have herein described the construction and, arrangement of machinery which I have essayed with success; but I do not wish to limit myself to the specified construction and arrangement, as these maybe modified without changing the principleof my invention.

What I claim as my invention, and desire to secure by Letters Patent in the method herein described of finishing the headsin the manufacture of wood-screws,is

Partly shaving the head with acutter before nicking, and after nicking subjecting it to a second shaving operation to complete the shaving by means of a cutter whose edges form with each other a more acute angle than the edges of the cutter first employed, as herein specified. A

THOS. J. SLOA-N. Witnesses:

WM. BISHOP, CAUs'rEN BROWNE. 

